CN110103202B

CN110103202B - Multi-mode series-parallel mechanical arm based on movement bifurcation mechanism

Info

Publication number: CN110103202B
Application number: CN201910271321.8A
Authority: CN
Inventors: 张春燕; 殷兴鲁; 宛宇; 刘香玉; 谢明娟; 李茂生; 朱锦翊
Original assignee: Shanghai University of Engineering Science
Current assignee: Shanghai University of Engineering Science
Priority date: 2019-04-04
Filing date: 2019-04-04
Publication date: 2022-06-24
Anticipated expiration: 2039-04-04
Also published as: CN110103202A

Abstract

The invention relates to a multi-mode hybrid mechanical arm based on a motion bifurcation mechanism, which comprises an end effector, an arm and a parallel base, wherein the end effector, the arm and the parallel base are sequentially connected, and the multi-mode hybrid mechanical arm comprises: the arm part is an 8-rod single-ring motion bifurcation mechanism and comprises two arm branch chains which are symmetrically arranged, two ends of the two arm branch chains are respectively and movably connected to form a single-ring closed chain structure, and each arm branch chain comprises four connecting rods which are sequentially and movably connected; the parallel base is a two-rotational-freedom-degree space parallel mechanism; and the parallel base is provided with a mode switching mechanism for realizing the serial and parallel conversion of the two arm branched chains. Compared with the prior art, the invention has the advantages of high working efficiency, small structural size and high overall stability.

Description

Multi-mode series-parallel mechanical arm based on movement bifurcation mechanism

Technical Field

The invention relates to the field of robot and machine manufacturing, in particular to a multi-mode hybrid mechanical arm based on a moving bifurcation mechanism, which can realize series-parallel switching of arms.

Background

At present, the application occasions of robots are diversified, and particularly for application scenes such as ultra-large mechanical equipment, special environment operation, production lines with various station properties and the like, the working conditions that the size is larger than that of a common mechanical structure, the station properties are various, and parts are various exist, while the traditional machining and assembling operation equipment has the limitation of single operation mode.

One of the previous solutions is to improve the working efficiency and quality by using a parallel mechanism and utilizing the characteristics of high rigidity and high precision of the parallel mechanism, but the solutions have the inherent defect of the parallel mechanism, namely, the working space is small. The other is that by increasing the number of the robots, different processing robots are needed to complete stations with different properties, and the scheme greatly increases the production input cost, often limits the task execution capacity of the robots, consumes working time and reduces the working efficiency. In the prior art, a plurality of parallel mechanisms are further connected in series to form a mechanical configuration, but the system has more kinematic pairs and a complex process for establishing a coordinate motion coordinate.

In order to effectively improve the processing efficiency of a large mechanical structure, better ensure the working quality and enable an operating device to select a better operating mode according to the task property, a processing robot which can simultaneously provide a plurality of different operating modes and is convenient to operate is developed, which is a technical problem to be solved urgently.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a multi-mode hybrid mechanical arm based on a motion bifurcation mechanism.

The purpose of the invention can be realized by the following technical scheme:

a multi-mode series-parallel mechanical arm based on a motion bifurcation mechanism comprises an end effector, an arm and a parallel base which are connected in sequence, wherein:

the arm part is an 8-rod single-ring motion bifurcation mechanism and comprises two arm branch chains which are symmetrically arranged, two ends of the two arm branch chains are respectively and movably connected to form a single-ring closed chain structure, and each arm branch chain comprises four connecting rods which are sequentially and movably connected;

the parallel base is a two-rotational-freedom-degree space parallel mechanism;

and the parallel base is provided with a mode switching mechanism for realizing the serial and parallel conversion of the two arm branched chains.

Further, the four links of each arm branch chain are different in shape.

Furthermore, the connecting rods are connected through rotating pairs, and a part of the connecting rods are provided with driving motors.

Further, the parallel base comprises an upper platform, a lower platform, a branched chain mechanism and a branched chain driving mechanism, the branched chain mechanism is movably connected between the upper platform and the lower platform, the branched chain driving mechanism is connected with the branched chain mechanism, the mode switching mechanism is installed on the upper platform, and the lower platform is installed on a fixed base plate.

Furthermore, the branched chain mechanism comprises three branched chains and a middle branched chain, the middle of the three branched chains is symmetrically provided with an upper platform and a lower platform edge, each branched chain comprises two movably connected connecting rods, the middle branched chain comprises a fixing rod I, a middle connecting piece and a fixing rod II which are movably connected in sequence, the fixing rod I is fixedly connected with the upper platform, and the fixing rod II is fixedly connected with the lower platform.

Furthermore, the two connecting rods of each branched chain are connected through an equivalent spherical pair.

Furthermore, the number of the branched chain driving mechanisms is three, and the branched chain driving mechanisms are respectively and correspondingly connected with the three branched chains.

Further, the branched chain driving mechanism is a screw rod driving mechanism, and the screw rod driving mechanism is fixed on the fixed bottom plate.

Further, the mode switching mechanism comprises a servo motor, a gear assembly and a transmission pin which are sequentially connected, and the transmission pin is connected with the arm branched chain.

Furthermore, the two mode switching mechanisms are correspondingly connected with the two arm branch chains respectively, and are arranged on the parallel base in a nesting mode.

The invention is different from the characteristic that the traditional mechanical arm only has a single operation mode, can realize two operation modes of series connection and plane parallel connection, integrates the large working space of a series configuration and the high rigidity of a parallel mechanism, and solves the problem that the series configuration and the parallel configuration are dual-complementary in performance but cannot be considered simultaneously. Compared with the prior art, the invention has the following beneficial effects:

(1) the arm part of the invention adopts the single-ring 8-rod motion branching mechanism, can conveniently realize the switching of two modes of series connection and plane parallel connection through the mode switching mechanism, has the advantages of large working space of a series mechanical arm and high rigidity of a parallel mechanism in function, has strong environmental adaptability and high working efficiency, solves the problems of single operation mode and poor environmental adaptability of the traditional operation equipment, can meet the conditions of processing and assembling, special environmental operation, production lines with various station properties and the like of ultra-large mechanical equipment, can meet the application requirements of various operation task properties, can select a more suitable operation mode from the two operation modes to complete a task in the face of different working conditions, ensures that the mechanical arm has better adaptability, and improves the working efficiency and the completion quality.

(2) The whole structure of the invention adopts a series-parallel connection structure, one device can complete the task which can be completed by two devices, the production input cost of mechanical equipment is obviously reduced, the structure size of the product is structurally reduced, the storage space is reduced, the transportation is convenient, and the transportation cost (especially for aviation transportation) is reduced.

(3) The arm part integrates the two previous operating devices into one structure, functionally combines the performance advantages of large working space of the serial mechanical arm, high rigidity of the parallel mechanism and the like, allows the mechanical arm to select a better operating mode to execute tasks according to different working conditions, and has better environmental adaptability, thereby improving the working efficiency and ensuring better finishing quality.

(4) The invention adopts the two-rotational-freedom-degree 3-RSR/S parallel mechanism as the base, fully utilizes the characteristics of high rigidity and high bearing capacity of the parallel mechanism, simultaneously increases the working space of the mechanical arm, and improves the stability, precision and rigidity of the mechanism.

(5) The intermediate joints of the four branch chains contained in the 3-RSR/S parallel mechanism are all provided with the equivalent spherical pair to replace a common spherical pair, so that the lubrication and the maintenance are easier, the physical interference is reduced, and the moving range is enlarged. The equivalent spherical pair has the characteristic that 3 revolute pairs intersect at one point, the general spherical pair is difficult to lubricate and maintain, inherent physical interference exists, the most serious defect is that the movable range is small, and the equivalent spherical pair is obviously improved in the performances.

(6) The arm part of the robot can be switched to a 2-RRR plane six-rod mode, the plane parallel mechanism in the configuration is of a structure with two branched chains, physical interference among connecting rods is effectively reduced, the working space is larger, the robot is different from a 3-RRR mechanism which is widely applied in the past, more degrees of freedom can be provided compared with a 5-rod plane operation robot which is widely applied, and the robot has better flexibility.

(7) The arm is a 3-axis series-connection mechanical arm and has 3 degrees of freedom, the connection mode of the arm and the upper platform increases one degree of freedom of rotation around the Z axis, the 3-RSR/S (R is a revolute pair, and S is a ball pair) parallel mechanism has 2 degrees of freedom of rotation, and the hybrid mechanical arm has 6 degrees of freedom as a whole and high flexibility.

(8) Theoretically, the mode switching is realized according to the singular position type of the 8-rod single-ring motion bifurcation mechanism; from the actual drive scheme, two sets of gear rings are respectively driven by two servo motors arranged on the upper platform, and furthermore, the opening and closing of two parallel branches of the arm are respectively driven by two transmission pins, so that the mode switching control of the arm is realized.

Drawings

FIG. 1 is a perspective view of the overall structure of the present invention;

FIG. 2 is a schematic view of the connection of the end effector to the arm and to the upper platform of the parallel base;

FIG. 3 is a schematic view of the robot arms in tandem mode, wherein (3a) is a general structural schematic view and (3b) is an overall mechanical schematic view;

FIG. 4 is a schematic view of the robot arm in a six-bar plane parallel mode, wherein (4a) is a schematic overall structure and (4b) is a schematic overall mechanical diagram;

FIG. 5 is a perspective view of the arm structure;

FIG. 6 is a schematic view of the mounting of the arm drive motor;

FIG. 7 is a schematic view of the arms in parallel mode, wherein (7a) is a schematic view of the structure and (7b) is a schematic view of the overall mechanism;

FIG. 8 is a schematic view of the arms in series mode, wherein (8a) is a schematic structural view and (8b) is a schematic overall mechanical view;

FIG. 9 is a schematic diagram showing the states of the arm mode switching process, wherein (9a) is the series configuration branch, (9b) is the singular bit type I, (9c) is the transition state I, (9d) is the transition state II, (9e) is the transition state III, (9f) is the singular bit type II, and (9g) is the planar six-bar configuration branch;

FIG. 10 is a schematic view of a 3-RSR/S parallel mechanism, wherein (10a) is a schematic view of the structure and (10b) is a schematic view of the overall mechanism;

FIG. 11 is an enlarged view of a portion of the upper surface of the upper platform of the 3-RSR/S parallel mechanism;

FIG. 12 is an enlarged view of a portion of the lower surface of the upper platform of the 3-RSR/S parallel mechanism;

FIG. 13 is an enlarged view of a portion of the lower portion of the motor mounting base;

FIG. 14 is a schematic diagram of the explosive structure of the intermediate 3R branched chain of the 3-RSR/S parallel mechanism;

FIG. 15 is a schematic view of a mode switching mechanism;

fig. 16 is a schematic diagram of an explosive structure of the branched chain driving mechanism.

The reference numbers in the figures illustrate:

1. the connecting rod I, the connecting rod II, the connecting rod III, the connecting rod IV, the connecting rod V, the connecting rod VI, the connecting rod VII, the connecting rod VIII, the upper chain connecting rod 9, the lower chain connecting rod 10, the lower platform 11, the upper platform 12, the upper platform 13, the inner gear ring 14, the outer gear ring 15, the outer gear 16, the inner gear 17, the transmission pin I, the transmission pin 18, the transmission pin II, the threaded hole I, the threaded hole 20, the double-headed connecting bolt 21, the driven bevel gear 22, the threaded hole II, the threaded hole 23, the driving bevel gear 24, the bolt 25, the transmission shaft I, the transmission shaft 26, the sliding block 27, the fixed bottom plate 28, the lead screw 29, the bolt I, the rotating bearing seat 30, the rotating bearing 31, the lead screw nut 32, the lead screw motor 33, the linear bearing 34, the bolt II, the sliding rod 36, the connecting pin 37, the central branched chain connecting rod I, the central branched chain connecting rod II, 40. the rotary bearing I, 41, the fixed rod I, 42, the fixed rod II, 43, the rotary bearing II, 44, the transmission shaft II, 45, the transmission shaft III, 46, the bolt III, 47, the end effector, 48, the bolt, 49, the hole I, 50, the hole II, 51, the servo motor, the M1-M3 driving motor and the R1-R13 rotary kinematic pair.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

As shown in fig. 1-2, the present embodiment provides a multi-mode hybrid manipulator based on a motion bifurcation mechanism, including an end effector 47, an arm, and a parallel base, which are connected in sequence, where the arm is an 8-rod single-ring motion bifurcation mechanism, and includes two symmetrically arranged arm branches, two ends of the two arm branches are respectively and movably connected to form a single-ring closed chain structure, each arm branch includes four connecting rods that are movably connected in sequence, and the arm and the parallel base play a role in limitation through a bolt iii 46; the parallel base is a two-rotational freedom degree space parallel mechanism; and the parallel base is provided with a mode switching mechanism for realizing the serial and parallel conversion of the two arm branched chains. As shown in fig. 3 and 4, the robot arm can rapidly realize series and plane parallel modes under the action of the mode switching mechanism. The mechanical arm is innovatively applied to the design of the mechanical arm by the 8-rod single-ring motion bifurcation mechanism, two modes of the mechanical arm are realized, the series-parallel mechanical arm with the arm capable of realizing series/parallel switching is designed, and the problem of single operation mode of the traditional mechanical arm is solved.

Functionally speaking: the arm part of the mechanical arm has the performance advantages of large working space of the serial mechanism, high rigidity and high precision of the parallel mechanism, and a more appropriate operation mode can be selected from two operation modes in the face of different working conditions, so that the mechanical arm has better adaptability, and the working efficiency and the finishing quality are improved.

Structurally, the method comprises the following steps: the invention integrates two configurations by means of the 8-rod single-ring motion branching mechanism, on one hand, one device can complete the task which can be completed by two devices, and the production input cost of mechanical equipment can be obviously reduced; on the other hand, the structure size is reduced, the storage space is reduced (for example, the storage space is an extremely important design index for air carrying equipment), the transportation is convenient, and the transportation cost is reduced. Meanwhile, the whole structure adopts a hybrid structure, the parallel mechanism is used as a base, the characteristic of high bearing capacity of the parallel mechanism is fully utilized, the working space of the mechanical arm is increased, and the working performance of the mechanism is improved.

The arm includes two bilateral symmetry arm branch chains, and 4 connecting rods that the shape is different promptly are connected through the revolute pair, form a monocycle closed chain structure, and have arranged driving motor on part connecting rod, are located 6 revolute pair axis of two arm branch chains and are parallel to each other to it is perpendicular in head end and terminal two revolute pairs.

The three-dimensional structure diagram of the arm in the embodiment is shown in fig. 5, wherein a connecting rod I1 and a connecting rod V5, a connecting rod III 3 and a connecting rod IV 4, a connecting rod IV 4 and a connecting rod VIII 8, a connecting rod VIII 8 and a connecting rod VII 7, and a connecting rod VII 7 and a connecting rod VI 6 are sequentially connected through revolute pairs R1, R2, R3, R4 and R5; the driving motors M1, M2 and M3 are sequentially arranged between the connecting rod I1 and the connecting rod II 2, between the connecting rod II 2 and the connecting rod III 3 and between the connecting rod V5 and the connecting rod VI 6 and are connected through revolute pairs, and the driving motors are fixed on the connecting rods through four bolts 48, as shown in fig. 6.

The arm part can realize two modes of series connection and plane parallel connection by using a singular position type, wherein in the plane parallel connection mode, the arm part has two degrees of freedom of movement and rotation, and in the series connection mode, the arm part has 3 degrees of freedom. In the singular position type shown in fig. 7, the revolute pair R1 is collinear with R3, the axes of M1, M2, M3, R2, R4 and R5 are all parallel to each other, and the axes of the revolute pairs R1 and R3 are perpendicular to the axes of M1, M2, M3, R2, R4 and R5. Fig. 9 is a schematic diagram showing the states of the arm mode switching process.

The parallel base adopts a 3-RSR/S parallel mechanism, the parallel mechanism can provide two rotational degrees of freedom, the parallel mechanism serves as the base to increase the working space, and the characteristic of high bearing capacity of the parallel mechanism is fully utilized. As shown in fig. 10 to 14, the parallel base includes an upper platform 12, a lower platform 11, a branch chain mechanism and a branch chain driving mechanism, the branch chain mechanism is movably connected between the upper platform 12 and the lower platform 11 through a revolute pair, the branch chain driving mechanism is connected with the branch chain mechanism, the mode switching mechanism is installed on the upper platform 12, and the lower platform 11 is installed on a fixed base plate 27 through a stud connecting bolt 20.

The branched chain mechanism comprises three branched chains and a middle branched chain. The middle of the three branched chains is symmetrically provided with the edges of the upper platform and the lower platform, namely the three branched chains are uniformly arranged between the upper platform and the lower platform at intervals of 120 degrees in sequence, and the structures of the three branched chains are the same. Each branch chain comprises two movably connected connecting rods, an upper chain connecting rod 9 is connected with an upper platform 12 through a revolute pair R6, a lower chain connecting rod 10 is connected with a lower platform 11 through a revolute pair R10, and the connecting rod 9 and the connecting rod 10 are connected through an equivalent spherical pair of which the axes R7, R8 and R9 of the 3 revolute pairs intersect at one point.

As shown in fig. 14, the middle branched chain includes a fixing rod i 41, a middle connecting member and a fixing rod ii 42 movably connected in sequence, the fixing rod i 41 is fixedly connected with the upper platform 12 through a threaded hole i 19, and the fixing rod ii 42 is fixedly connected with the lower platform 11 through a threaded hole ii 22. The middle connecting piece comprises a central branched chain connecting rod I38 and a central branched chain connecting rod II 39 which are connected through a connecting pin 37, the central branched chain connecting rod I38 (the central branched chain connecting rod II 39) is connected with a fixed rod II 42 (the fixed rod I41) through a revolute pair R11 (a revolute pair R13), and a rotary bearing II 43 (a rotary bearing I40) is arranged in the middle of the central branched chain connecting rod I38 and plays roles of fixing, supporting and reducing friction.

The three branched chain driving mechanisms are respectively and correspondingly connected with the three branched chains and used as three input variables of the 3-RSR/S parallel mechanism. In this embodiment, the branched chain driving mechanism is a screw driving mechanism, and the screw driving mechanism is fixed on the fixed base plate. As shown in fig. 16, the screw rod driving mechanism includes a driving motor 33, a fixed base plate 27, a screw rod 28, a screw rod nut 32, a slider 26, a sliding rod 36, a rotating bearing 31, a linear bearing 34 and a rotating bearing seat 30, the screw rod motor 33 is fixed on the bottom surface of the fixed base plate 27 through a bolt ii 35, and outputs rotation through the screw rod, the tail end of the screw rod motor plays a role in supporting the screw rod through the rotating bearing 31 installed on the rotating bearing seat 30, and the rotating bearing seat is fixed on the fixed base plate 27 through a bolt i 29; the screw rod nut 32 is arranged on the screw rod 28 and is fixedly connected with the slide block 26, the slide block 26 is connected with the slide rod 36 through the linear bearing 34 arranged in the slide block, and the slide rod 36 is connected with the lower chain connecting rod 10 through the revolute pair R13. The driving of the other two branches is effected in the same way.

The mode switching mechanism can be provided with one or two, and is respectively and correspondingly connected with the two arm branched chains, so that one or two of the arm branched chains can act. When the number of the mode switching mechanisms is two, the two mode switching mechanisms are arranged on the parallel base in a nesting mode. The mode switching mechanism comprises a servo motor, a gear assembly and a transmission pin which are connected in sequence, and the transmission pin is connected with the arm branched chain.

As shown in fig. 15, the configuration of the mode switching mechanism will be described by taking one example. The servo motor 51 is fixed on the bottom surface of the upper platform 12 through a bolt 24, an output shaft is fixed with the driving bevel gear 23 through pin connection, the driven bevel gear and the outer side gear 15 are both fixedly connected with the transmission shaft 42, and gear transmission is performed between the driven bevel gear 21 and the driving bevel gear 23; as shown in fig. 11, on the upper platform 12, the outer gear 15 drives the outer gear ring 14 to rotate through gear transmission, the outer gear ring 14 is provided with a transmission pin 17, the transmission pin 17 can be inserted into the hole i 49 and connected through a revolute pair, so as to output torque, play a driving role, realize the opening and closing of two branched chains of the arm, and complete the switching between the two modes.

Two modes are introduced and the mode switching principle is explained:

the arm part of the multi-mode series-parallel mechanical arm realizes two operation modes of series connection and parallel connection based on a single-ring motion branching mechanism, and the series connection configuration has the characteristics of large working space and simple structure; the parallel configuration has the advantages of high rigidity and high precision. The invention has the excellent characteristics of two configurations, so that when the mechanical arm works in different properties, a more suitable one can be selected, and the performance of the mechanism is improved.

Series mode: the tandem mode, as shown in fig. 8, can be used to perform tasks where the operational target is relatively lightweight, and where the accuracy requirements are low and the operating range requirements are large. The 3-axis serial mechanical arm has 3 degrees of freedom, the arm is connected with the upper platform in a mode shown in figure 2, so that one degree of freedom of rotation around the Z axis is increased, the base 3-RSR/S parallel mechanism has two degrees of freedom of rotation, and the hybrid mechanical arm has 6 degrees of freedom integrally.

Plane parallel mode: as shown in fig. 7, the planar parallel structure has greater rigidity and higher load-bearing capacity than the serial configuration, and the parallel structure has no accumulated error, has better precision, and can be used for performing tasks requiring high precision and having relatively large weight, particularly for performing operations in a two-dimensional planar space, such as: and (5) selecting and assembling. The configuration is a 2-RRR plane six-bar structure, and the structure is composed of two identical branched chains which are symmetrical left and right to form a single-ring closed chain. The configuration has two degrees of freedom of movement in a plane and one degree of freedom of rotation perpendicular to the plane. The common planar five-bar parallel mechanism has 2 degrees of freedom of movement, and the configuration provides better flexibility; the widely used 3-RRR plane parallel mechanism has three branched chains, and the configuration only has 2 branched chains, so that the physical interference between connecting rods is effectively avoided, and the working space range is further expanded by using a parallel mechanism base.

The following takes the switching of the arm from the series mode to the planar parallel mode as an example, and the specific process of switching is explained from both theoretical and practical driving aspects:

1. the theory level shows that:

as shown in fig. 9, (9a) to (9g) specify the following mathematical expressions for simplifying the explanation, in order to realize the mode switching process of the robot arm from the series configuration branch to the two singular bit types:

the axes of the revolute joint revolute pairs are represented by R1-R5 and M1-M3;

(II) R1 is not equal to R2 to indicate that the two corresponding axes are not collinear; the plane of the two branched chains is represented by pi 1 and pi 2;

using alpha to represent the included angle between pi 1 and pi 2; the included angle between R1 and R3 is represented by beta;

(9a) the mechanism is entered into a branch of a serial configuration. The revolute pair R1 and the axis of R3 form a certain angle, R1 is not equal to R3, and alpha is 0 degree;

(9b) the mechanism is in a singular position type I at the moment, the two chains are respectively superposed with corresponding connecting rods, the axes M1 are superposed with M2, M3 is superposed with R5, and R3 is superposed with R4, and the position type is as follows: α ═ 0 °, R1 ═ R3; the mechanism is in a critical state at the moment, can enter a series configuration, and can also enter another singular position type II by increasing alpha to 180 degrees;

(9c) (9e) a transitional state of a singular bit type II in which the mechanism gradually increases alpha to 180 degrees;

(9f) the mechanism is of another singular position type II, the two chains are respectively corresponding to the connecting rods to be coplanar, and the position type is as follows: α ═ 180 °, R1 ═ R3, M1/M2/M3/R5/R3/R4; the mechanism is in another critical state, either entering a planar six-bar configuration branch as shown in fig (9g) or entering another singular configuration i by gradually reducing a up to 0 degrees.

(9g) The mechanism enters a plane six-rod configuration branch. The revolute pair R1 forms a certain angle with the axis of R3, R1 is not equal to R3, and alpha is 180 degrees.

By the above processes of (9a) to (9g), the mechanism gradually realizes mode switching from the series operation mode to the planar six-bar operation mode.

2. Description from the practical drive level:

assuming that one branched chain of the plane parallel mechanism is fixed, only the other branched chain is driven to realize mode conversion, and actually, both the two branched chains can rotate simultaneously so as to improve the response speed and quickly realize mode switching. The initial position of the mechanism is in a series configuration as shown in a figure (9a), a servo motor 51 is started and drives a driving bevel gear 23 fixed on an output shaft of the servo motor, a driven bevel gear 21 is further driven through gear transmission, a gear 15 fixed on the driving bevel gear is further driven to rotate through a transmission shaft 25, the gear 15 further drives an outer gear ring 13 to rotate, a transmission pin I is arranged on the gear ring, the transmission pin is inserted into a hole 49 positioned at the bottom of a connecting rod 1 to output torque and drive a branched chain to rotate, alpha is gradually increased from 0 degrees to 180 degrees through the processes of figures (9c) to (9e), and the final state is in a plane parallel mode as shown in a figure (9f), so that the switching from the series mode to the plane parallel mode is realized.

In the case of replacing a certain mechanism included in the present invention with a mechanism having a similar function or similar structure to implement the idea of the solution described in the present invention, such equivalent modifications or replacements are included in the scope defined in the claims of the present application.

By changing the structural appearance of the bar or replacing some part of the invention with a mechanism with the same performance characteristics, and applying it in the case of other fields of application (not robotic arms), for example: the mechanism used for the bionic robot deformation leg and other biological limbs is designed and also included in the scope defined by the claims of the application.

The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations can be devised by those skilled in the art in light of the above teachings. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.

Claims

1. The utility model provides a multi-mode series-parallel mechanical arm based on motion bifurcation mechanism which characterized in that, includes end effector, arm and the parallelly connected base that connects gradually, wherein:

the parallel base is a two-rotational-freedom-degree space parallel mechanism;

2. The multi-mode hybrid robot arm based on a motion forking mechanism of claim 1, wherein the four links of each arm branch are different in shape.

3. The multi-mode hybrid mechanical arm based on the motion bifurcation mechanism according to claim 1, wherein the connecting rods are connected with each other through revolute pairs, and a part of the connecting rods are provided with driving motors.

4. The multi-mode hybrid mechanical arm based on a motion bifurcation mechanism according to claim 1, wherein the parallel pedestal comprises an upper platform, a lower platform, a branch chain mechanism and a branch chain driving mechanism, the branch chain mechanism is movably connected between the upper platform and the lower platform, the branch chain driving mechanism is connected with the branch chain mechanism, the mode switching mechanism is installed on the upper platform, and the lower platform is installed on a fixed base plate.

5. The multimode hybrid manipulator based on a moving bifurcation mechanism as claimed in claim 4, wherein the branched chain mechanism comprises three branched chains and a middle branched chain, the three branched chains are centrosymmetrically arranged at the edges of the upper platform and the lower platform, each branched chain comprises two movably connected connecting rods, the middle branched chain comprises a fixing rod I, a middle connecting piece and a fixing rod II, which are movably connected in sequence, the fixing rod I is fixedly connected with the upper platform, and the fixing rod II is fixedly connected with the lower platform.

6. The multi-mode hybrid mechanical arm based on the motion bifurcation mechanism according to claim 5, wherein the two connecting rods of each bifurcation are connected by an equivalent spherical pair.

7. The multi-mode hybrid mechanical arm based on the motion fork mechanism as claimed in claim 4, wherein there are three branched driving mechanisms respectively connected to the three branched chains.

8. The multi-mode hybrid mechanical arm based on the motion fork mechanism as claimed in claim 4, wherein the branched driving mechanism is a lead screw driving mechanism, and the lead screw driving mechanism is fixed on the fixed base plate.

9. The multi-mode hybrid mechanical arm based on a motion bifurcation mechanism according to claim 1, wherein the mode switching mechanism comprises a servo motor, a gear assembly and a driving pin which are connected in sequence, and the driving pin is connected with the arm branch chain.

10. The multi-mode hybrid mechanical arm based on a motion bifurcation mechanism according to claim 8, wherein two mode switching mechanisms are respectively connected with the two arm branches, and the two mode switching mechanisms are arranged on the parallel bases in a nested manner.